1. Field of the Invention
The present invention relates to a head slider used when height (glide height) of a projection on a surface of a magnetic disk is checked, a glide height checking apparatus having the head slider, and a glide height checking method using the head slider.
2. Background Art
A magnetic disk device performs write and read while a magnetic head is allowed to fly by an airflow accompanying rotation of a magnetic disk. Flying height of a magnetic disk (hereinafter, simply called “flying height”) is reduced in accordance with increase in write density of the magnetic disk, and has been decreased to be less than 10 nm in recent years. However, when flying height is less than 10 nm, the magnetic head tends to be contacted to a projection on a surface of the magnetic disk, so that a property of the magnetic head is possibly changed due to friction heat or deformation caused by such contact. Therefore, in the magnetic disk, the projection on the surface is similarly reduced by accurate surface processing (varnishing), and height of the projection (glide height) has been required to be decreased to be less than 4 nm in recent years.
While the glide height is checked by using a glide height checking apparatus having a special head slider, when the glide height is decreased to be less than 4 nm as described above, it is necessary that the head slider is allowed to accurately fly with a flying height of less than 4 nm. That is, the head slider must be allowed to fly with a flying height extremely lower than a flying height in the case of the magnetic head of the magnetic disk device.
Usual glide height checking apparatuses are disclosed in Japanese Unexamined Patent Publications No. 10-27342, No. 2006-31886, No. 9-259401, and No. 9-128745.